Vehicle occupant restraint system

ABSTRACT

A vehicle occupant restraint system including: a seatbelt device including a shoulder belt portion restraining a part of a vehicle occupant from one of shoulders to a chest, and a lap belt portion restraining a waist of the vehicle occupant; an upper airbag provided in the shoulder belt portion, and configured to be deployed forward from the shoulder belt portion; a lower airbag provided in the lap belt portion, and configured to be deployed forward from the lap belt portion, the deployed upper and lower airbags coming into contact with each other in a vertical direction; and a movement restraining portion restraining relative movement of the deployed upper and lower airbags in a front-rear direction, extending downward from a lower side of the deployed upper airbag, and positioned in the rear of the deployed lower airbag.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicle occupant restraint system forprotecting an occupant of a vehicle when the vehicle detects or predictsa collision.

2. Description of the Related Art

Japanese Patent Application Laid-Open Publication No. 2006-160062discloses a vehicle occupant restraint system which has airbagsinstalled inside a seatbelt and is configured to protect an occupant ofa vehicle by deploying the airbags when a front collision of the vehicleoccurs.

In the above system, an upper airbag and a lower airbag are respectivelyinstalled inside a shoulder belt portion and a lap belt portion whichform the seatbelt. Additionally, when a collision of the vehicle occurs,the upper and lower airbags are prevented from being displaced from eachother in a front-rear direction of the vehicle by individually deployingthe upper and lower airbags so that a lower face of the upper airbag cancome into contact with an upper face of the lower airbag.

SUMMARY OF THE INVENTION

In the above vehicle occupant restraint system, a frictional forcegenerated by direct contact between the lower face of the upper airbagand the upper face of the lower airbag prevents the upper and lowerairbags from being displaced from each other in the vehicle front-reardirection. However, in the cases where an inertial force acting on thevehicle occupant during breaking of the vehicle is large and whereforces of deployment of the upper and lower airbags are large, thefrictional force may be insufficient for reliably preventing thedisplacement.

The present invention was made in consideration of the above problem,and an object of the present invention is to provide a vehicle occupantrestraint system capable of deploying an upper airbag and a lower airbaginstalled in a seatbelt while maintaining their proper relativepositions in a front-rear direction of a vehicle.

An aspect of the present invention is a vehicle occupant restraintsystem including: a seatbelt device including a shoulder belt portionfor restraining a part of a vehicle occupant from one of shoulders to achest, and a lap belt portion for restraining a waist of the vehicleoccupant; an upper airbag provided in the shoulder belt portion, andconfigured to be deployed forward from the shoulder belt portion when acollision of the vehicle is detected or predicted; a lower airbagprovided in the lap belt portion, and configured to be deployed forwardfrom the lap belt portion when a collision of the vehicle is detected orpredicted, the deployed upper and lower airbags coming into contact witheach other in a vertical direction; and a movement restraining portionfor restraining relative movement of the deployed upper and lowerairbags in a front-rear direction, the movement restraining portionextending downward from a lower side of the deployed upper airbag, andpositioned in the rear of the deployed lower airbag.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings wherein:

FIG. 1 is a side view of a vehicle occupant fastening a seatbelt deviceaccording to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a state where the upper airbag andthe lower airbag according to the first embodiment of the presentinvention are deployed.

FIG. 3 is a front view of the upper airbag according to the firstembodiment of the present invention, which is yet to be deployed and isprovided with a first movement restraining portion.

FIG. 4 is a perspective view of the lower airbag according to thepresent invention.

FIG. 5 is a side view of a state where the upper airbag and the lowerairbag according to the first embodiment of the present invention aredeployed.

FIG. 6 is schematic views explaining a tensile force acting on the upperairbag according to the first embodiment of the present invention. FIG.6( a) shows a pressurized state inside the upper airbag when a fluid issupplied into the inside of the upper airbag. FIG. 6( b) shows a tensileforce acting upon the first movement restraining portion due to thepressures inside the upper airbag which are shown in FIG. 6( a).

FIG. 7 is a front view of an upper airbag according to a secondembodiment of the present invention, which is yet to be deployed andprovided with a second movement restraining portion.

FIG. 8 is a front view showing an upper airbag according to a thirdembodiment of the present invention, which is yet to be deployed.

FIG. 9 is a side view of a state where the upper airbag shown in FIG. 8and a lower airbag are deployed.

FIG. 10 is side views showing operations of vehicle occupant restraintsystems according to the first to third embodiments of the presentinvention, and FIGS. 10( a), (b) and (c) show an initial stageimmediately following detection or prediction of a vehicle collision, anintermediate stage following the initial stage, and a late stage, wherea lower airbag bends, following the intermediate stage, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings.

First Embodiment

A vehicle occupant restraint system according to a first embodiment ofthe present invention will be described with reference to FIG. 1. Notethat, although a vehicle occupant restraint system arranged for aright-side rear seat of a vehicle will be described as an example inthis embodiment, the system can be applied to seats in other positions.

Additionally, in the present invention, the upper airbag and the lowerairbag are deployed when a vehicle collision detection/prediction system“detects” or “predicts” a collision of the vehicle. Here, the“detection” or “prediction” is not limited to a case where a collisionload inputted to the vehicle is detected, but broadly includes, forexample, such cases as where a running speed decrease of the vehicle isdetected, where a situation that the vehicle is expected to come intocontact with an obstacle is detected, and where a collision with anobstacle is predicted by external environment detection means formed byan ultrasonic sensor, a laser radar, a camera or the like.

A seatbelt device 22 in this embodiment is a three-point seatbeltdevice, and restraints a vehicle occupant 15 by using three points assupporting points, the three points being: a shoulder anchor portion 7arranged in an upper position in the right side (the outer side in awidth direction of the vehicle) of the vehicle occupant 15; anunillustrated lap anchor portion arranged in a lower position in theright side (the outer side in the vehicle width direction) of thevehicle occupant 15; and an unillustrated buckle anchor portion arrangedin a lower position in the left side (the inner side in the vehiclewidth direction) of the vehicle occupant 15. These shoulder anchorportion 7, lap anchor portion and buckle anchor portion may be fixed toa vehicle body, or may be fixed to a vehicle seat 6.

The seatbelt device 22 is provided with a shoulder belt portion 11 and alap belt portion 13. The shoulder belt portion 11 is provided toobliquely extend from the anchor portion 7 to a buckle portion 9, andrestrains a part of the vehicle occupant 15 from a right shoulder 17 toa chest 19. The lap belt portion 13 is provided to extend from the lapanchor portion to the buckle portion 9, and restrains a waist 21 of thevehicle occupant 15. Note that, in FIG. 1, reference numerals 23 and 25indicate a head and a femoral region of the vehicle occupant 15,respectively.

FIG. 2 is a perspective view showing a state where the upper airbag andthe lower airbag according to the first embodiment of the presentinvention have been deployed.

When the vehicle collision detection/prediction system detects orpredicts a collision of the vehicle, a command signal is transmittedfrom the vehicle collision detection/prediction system to an inflatorvia an airbag control module, and the inflator supplies a pressurizedgas to the upper airbag 27 and the lower airbag 29. Thereby, as shown inFIG. 2, the upper airbag 27 and the lower airbag 29 are deployed forwardof the shoulder belt portion 11 and the lap belt portion 13,respectively. That is, although being stored inside the shoulder beltportion 11 at normal times (when a collision of the vehicle has not yetbeen detected or predicted), the upper airbag 27 is deployed forward inthe vehicle front-rear direction from the shoulder belt portion 11 whena collision of the vehicle is detected or predicted. Then, the upperairbag 27 positions itself, in a deployed/inflated state, in front ofthe shoulder belt portion 11 and in front of the chest 19 of the vehicleoccupant 15 with a part of the upper airbag 27 being connected to theshoulder belt portion 11. Although being stored inside the lap beltportion 13 at the normal times, the lower airbag 29 is deployed forwardin the vehicle front-rear direction from the lap belt portion 13 when acollision of the vehicle is detected or predicted. Then, the lowerairbag 29 positions itself, in a deployed/inflated state, in front ofthe lap belt portion 13 and in front of an abdomen of the vehicleoccupant 15 with a part of the lower airbag 29 being connected to thelap belt portion 13. The deployed upper airbag 27 and the deployed lowerairbag 29 vertically come into contact with each other. That is, thedeployed upper airbag 27 is positioned upward of the lower airbag 29,and has a lower part thereof making direct contact with an upper part ofthe lower airbag 29.

Note that, when a braking force acts on the vehicle after a collision ofthe vehicle is detected or predicted, an inertial force forcing thevehicle occupant 15 to move forward in the vehicle front-rear directionrelative to a vehicle body (the seat 6) acts on the vehicle occupant 15.At this time, an upper body of the vehicle occupant 15 turns forwardabout the neighborhood of the waist 21 restrained by the lap beltportion 13, and a shoulder 17 of the shoulders 17, which is located inthe buckle portion 9 side where the shoulder 17 is not restrained by theshoulder belt portion 11, moves forward and downward of the vehicle dueto the inertial force. Thereby, a rotational moment M about a fixingportion 28, through which the upper airbag is fixed to the shoulder beltportion 11, is applied to the upper airbag 27 as shown in FIG. 2, forexample, in the clockwise direction from an anterior view if the vehicleoccupant 15 is on the right-side seat, or in the anticlockwise directionfrom an anterior view if the vehicle occupant 15 is on the left-sideseat.

FIG. 3 is a front view of the upper airbag according to the firstembodiment of the present invention, which is yet to be deployed and isprovided with a first movement restraining portion.

The upper airbag 27 is formed into a bag by sewing together marginalportions 95 of two sheet materials along a sewing line 97 substantiallyrectangular in a plan view, and has a pressurized gas inflow port 99provided to a bottom end portion thereof.

In a lower portion of the upper airbag 27, a concaved section 103 (aconcave portion 101) is formed where the sewing line 97 is formed into asubstantially V-shaped curve curved inward (toward the upper right sidein FIG. 3) with respect to the upper airbag 27 in a plan view. In thelower portion of the upper airbag 27, there is further provided thefirst movement restraining portion 109 linearly joining end portions 105and 107 which are both ends of the concaved section 103 in the vehiclewidth direction. That is, in the concaved section 103, the deployedupper airbag 27 has an outer surface having a shape concaved inwardly.Here, the end portion 105 is, out of the end portions of the concavedsection 103 having the outer surface concaved inwardly, an end portionin one side corresponding to where the anchor portion 7 of the shoulderbelt portion 11 is arranged (that is, out of the left and rightshoulders 17 of the vehicle occupant 15, the side corresponding to ashoulder restrained by the shoulder belt portion 11). On the other hand,the end portion 107 is, out of the end portions of the concaved section13, an end portion in one side corresponding to where the buckle portion9 of the shoulder belt portion 11 is arranged (that is, out of the leftand right shoulders 17 of the vehicle occupant 15, the sidecorresponding to a shoulder unrestrained by the shoulder belt portion11).

The first movement restraining portion 109 specifically is asubstantially triangular remainder of at least any one of the two sheetmaterials when the sheet materials are cut. In this embodiment, thefront-side sheet material is cut out, and a part of the back-side sheetmaterial is kept remaining in a substantially triangle shape. The firstmovement restraining portion 109 is provided so as to, in a lower sideof the deployed upper airbag 27, linearly join the end portion in oneside corresponding to where the anchor portion 7 (refer to FIG. 1) isarranged and the end portion in the other side corresponding to wherethe buckle portion 9 (refer to FIG. 1) is arranged. The upper airbag 27is thus integrally formed of: an upper airbag main body portion 93; andthe first movement restraining portion 109 provided along the vehiclewidth direction to a lower side portion of the upper airbag main bodyportion 93. Note that, when a pressurized fluid is supplied into theinside of the upper airbag main body portion 93 through the inflow port99, the upper airbag main body portion 93 inflates and is deployed.

The lower airbag 29 is formed, as shown in FIG. 4, by lapping afront-side sheet material 31 over a back-side sheet material 33, andjoining marginal portions 35 of these sheet materials to each otherthrough sewing or the like. In an upper portion of the front-side sheetmaterial 31, a pair of left and right round discharging holes 45 areformed.

Additionally, a part of an inner face of the front-side sheet material31 and a part of an inner face of the back-side sheet material 33 arejoined to each other in a front-rear direction by means of an deploymentregulating member 37 formed into a sheet. The deployment regulatingmember 37 is thus arranged inside the lower airbag 29, and sections inthe front-side sheet material 31 and the back-side sheet material 33 arepulled inward with respect to the lower airbag 29 and in a directionsubstantially parallel to the front-rear direction, the sections havingthe deployment regulating member 37 fixed thereto. Consequently, in thefront-rear direction, a thickness of the lower airbag 29 at a portionwhere the deployment regulating member 37 is fixed is smaller than thoseof the other portions, and a hollow 39 is formed on an outer surface ofthe lower airbag 29.

The deployment regulating member 37 thus regulates deployment of thelower airbag 29 in the front-rear direction when the lower airbag 29 isdeployed. A section in the lower airbag 29 which is upper than thedeployment regulating member 37 will be referred to as an upper section41, and a section in the lower airbag 29 which is lower than thedeployment regulating member 37 will be referred to as a lower section43. As has been described above, in the front-rear direction, athickness of the lower airbag 29 at the portion where the deploymentregulating member 37 is fixed is smaller than those of the otherportions. Consequently, the deployed lower airbag 29 becomes more likelyto bend about the portion where the deployment regulating member 37 isfixed, and the upper section 41 becomes moveable in a front-reardirection relatively freely as compared to the lower section 43.

FIG. 5 is a side view of a state where the upper airbag and the lowerairbag according to the first embodiment of the present invention aredeployed.

When the upper airbag 27 including the first movement restrainingportion 109 and the lower airbag 29 are deployed, the first movementrestraining portion 109 extends downward from the lower side of theupper airbag 27, and is positioned, with respect to the vehicle, in therear of the upper section 41 of the deployed lower airbag 29 (that is,between the upper section 41 of the lower airbag 29 and the vehicleoccupant 15), as shown in FIG. 5. Thus, the first movement restrainingportion 109 serves as a non-deploying portion in the upper airbag 27.

FIG. 6 is schematic views explaining a tensile force acting on the upperairbag according to the first embodiment of the present invention. FIG.6( a) shows a pressurized state inside the upper airbag when a fluid isflown into the inside of the upper airbag, and FIG. 6( b) shows atensile force acting on the first movement restraining portion due tothe pressures inside the upper airbag.

A supply pipe 111 connected to the inflator is fit to the inflow port 99formed in the bottom end portion of the upper airbag 27. The upperairbag 27 is deployed when a pressurized fluid is supplied from theinflator into the inside of the upper airbag 27 via the supply pipe 111.A pressure P uniformly acts on each of sections in the inner surface ofthe deployed upper airbag 27. Here, as has been described above, theconcaved section 103 (the concave portion 101) is provided in the upperairbag 27 where the upper airbag 27 has an outer surface concavedinwardly when deployed. Additionally, the pressure P acts on theconcaved section 103 in a manner pushing the concaved section 103 in anoutward direction with respect the upper airbag 27, whereby the endportions 105 and 107 of the concaved section 103 are forced to be moredistant from each other. Thereby, a tensile force T along an arrow inFIG. 6( b) acts on the first movement restraining portion 109.

Next, functions and effects produced by the first embodiment of thepresent invention will be described.

In this embodiment, the first movement restraining portion 109 isprovided which extends downward from the lower side of the deployedupper airbag 27, is positioned in the rear, in the vehicle front-reardirection, of the deployed lower airbag 29, and, when the deployed upperairbag 27 and the deployed lower airbag 29 comes into contact with eachother, restrains relative movement between the airbags 27 and 29 in thefront-rear direction.

Consequently, when the upper airbag 27 and the lower airbag 29 aredeployed and come into contact with each other after a collision of thevehicle is detected or predicted, relative movement between the upperairbag 27 and the lower airbag 29 in the front-rear direction can berestrained. Thereby, in a case where the vehicle occupant 15 movesforward due to an inertial force when breaking the vehicle, the upperairbag 27 and the lower airbag 29 can reliably protect a head 23 and thelike of the vehicle occupant 15. Additionally, it is prevented that theupper section 41 of the deployed lower airbag 29 intrudes into the rearof the deployed upper airbag 27, and thereby the proper transmission ofa supporting force of the lower airbag 29 to the vehicle occupant 15 issecured. Additionally, even when the deployed upper airbag 27 is forcedto move forward of the lower airbag 29 due to a load inputted from thevehicle occupant 15, the movement of the upper airbag 27 is prevented byhaving the first movement restraining portion 109 abutting to the uppersection 41 of the lower airbag 29. Thereby, relative positions of theupper airbag 27 and the lower airbag 29 in the vehicle front-reardirection can be properly maintained when the upper airbag 27 and thelower airbag 29 are deployed.

As a result, the head 23 of the vehicle occupant 15 can be more quicklyrestrained in a manner allowing the head 23 of the vehicle occupant 15bending forward to be received by the upper and lower airbags 27 and 29,and thereby allowing a load thereof to be supported by the femoralregions 25 of the vehicle occupant 15 or a seating face of a seatcushion 3 through the upper and lower airbags 27 and 29.

Additionally, the shoulder belt portion 11 is provided to extend, fromthe anchor portion arranged in one of the left and right sides of thesitting vehicle occupant 15 near the level of the corresponding left andright shoulders 17 thereof, to the buckle portion 9 arranged in theother side, and the first movement restraining portion 109 is providedto, in the lower side of the deployed upper airbag 27, join the endportion in the side corresponding to where the anchor portion 7 isarranged and the end portion in the side corresponding to where thebuckle portion 9 is arranged.

Consequently, when the upper airbag 27 is deployed, the tensile force Toccurs on the first movement restraining portion 109 located between theend portion in the side corresponding to where the anchor portion 7 isarranged and the end portion in the side where the buckle portion 9 isarranged. By the first movement restraining portion 109 made tense bythis tensile force T, intrusion of the upper section 41 of the lowerairbag 29 into the rear of the upper airbag 27 can be prevented. Thisprovides a reliable guide for the upper section 41 of the lower airbag29 by which the lower airbag 29 is securely bent and the upper section41 thereof securely falls forward in the vehicle front-rear direction.

Additionally, when a braking force acts on the vehicle after a collisionof the vehicle is detected or predicted, an inertial force forcing thevehicle occupant 15 to move forward in the vehicle front-rear directionrelative to the vehicle body (the seat 6) acts on the vehicle occupant15. At this time, the upper body of the vehicle occupant 15 turnsforward about the neighborhood of the waist 21 restrained by the lapbelt portion 13, and the shoulder 17 of the shoulders 17, which islocated in the buckle portion 9 side and is not restrained by theshoulder belt portion 11, moves forward and downward due to the inertialforce. Thereby, the rotational moment M about the fixing potion 28,through which the upper airbag is fixed to the shoulder belt portion 11,is applied to the upper airbag 27 as shown in FIG. 2, for example, inthe clockwise direction from an anterior view if the vehicle occupant 15is on the right-side seat, or in the anticlockwise direction from ananterior view if the vehicle occupant 15 is on the left-side seat. Bythis rotational moment also, the tensile force T is applied on the firstmovement restraining portion 109 of the upper airbag 27. By having thefirst movement restraining portion 109, on which the tensile force T hasbeen applied, abutting to the upper section 41 of the lower airbag 29,the upper airbag 27 is prevented from moving forward relative to thelower airbag 29, whereby relative positions of the upper airbag 27 andthe lower airbag 29 in the front-rear direction can be maintainedproperly.

Additionally, the concave portion 101 where the upper airbag 27 has theouter surface concaved inwardly when deployed is provided in the aboveupper airbag 27, and the first movement restraining portion 109 joinsthe end portions 105 and 107 of the concave portion 101 in the vehiclewidth direction.

Consequently, when a pressurized fluid 63 is supplied into the inside ofthe upper airbag 27, a pressure of the fluid 63 uniformly acts on anentirety of the inner surface of the upper airbag 27, and pushes theconcave portion 101 outward, whereby the tensile force T forcing theconcave portion 101 to be tense acts on the first movement restrainingportion 109. Thereby, the tensile force T is additionally applied on thefirst movement restraining portion 109.

Furthermore, the first movement restraining portion 109 is provided as anon-deploying portion in the upper airbag 27. Consequently, when theupper airbag 27 and the lower airbag 29 are deployed, the lower airbag29 and the first movement restraining portion 109 of the upper airbag 27are positioned in a state overlapping each other in the vehiclefront-rear direction. On the other hand, if the first movementrestraining portion 109 is provided as a deploying portion, the lowerairbag 29 and the first movement restraining portion 109 of the upperairbag 27 are deployed at the same time in a overlapping region, whichleads to a risk that an excessive force of deployment may be applied tothe vehicle occupant 15. Consequently, by setting a non-deployingportion in the upper airbag 27 as the first movement restraining portion109, a force of deployment applied on the vehicle occupant 15 can becontrolled.

Note that: the upper airbag 27 is formed by joining together themarginal portions 95 of the two sheet materials; the concave portion 101is the concaved section 103 obtained by arranging the joined portionsinward with respect to the upper airbag 27; and the first movementrestraining portion 109 is formed of a part of the sheet materials whichis arranged in the concaved section 103.

Consequently, production work of the first movement restraining portion109 can be made simple since the first movement restraining portion 109can be produced only by having a part of the marginal portions 95 notcut out, but left as it is.

Second Embodiment

Next, a vehicle occupant restraint system according to a secondembodiment of the present invention will be described. The samereference numerals are attached to the same sections as those of theabove described first embodiment, and description thereof will beomitted.

FIG. 7 is a front view of an upper airbag according to the secondembodiment of the present invention, which is provided with a secondmovement restraining portion.

This upper airbag 113 is formed of an upper airbag main body portion115, and the second movement restraining portion 117 which is a linearmember joining the end portions 105 and 107 of the concaved section 103of the upper airbag main body portion 115. To the second movementrestraining portion 117, any one of various linear members can beapplied as long as the one is an inelastic string, strip, and the like.Additionally, both ends of the second movement restraining portion 117can be fixed to the upper airbag main body portion 115 through sewing orthe like.

Next, functions and effects produced by the second embodiment of thepresent invention will be described.

In this embodiment, the second movement restraining portion 117 isformed of a linear member, whereby a length of the second movementrestraining portion 117 can be easily changed.

Third Embodiment

Next, a vehicle occupant restraint system according to a thirdembodiment of the present invention will be described. The samereference numerals are attached to the same sections as those of theabove described first and second embodiments, and description thereofwill be omitted.

FIG. 8 is a front view showing an upper airbag according to a thirdembodiment of the present invention, which is yet to be deployed, andFIG. 9 is a side view of a state where the upper airbag shown in FIG. 8and a lower airbag are deployed. As shown in FIG. 8, the upper airbag119 is integrally formed of: an upper airbag main body portion 121; thefirst movement restraining portion 109 provided to a lower side of theupper airbag main body portion 121; and an extended portion 123 providedon top of the upper airbag main body portion 121.

The extended portion 123 is a substantially trapezoidal remainder of atleast any one of two front-side and back-side sheet materials formingthe upper airbag main body portion 121 when the sheet materials are cut.In an upper end portion thereof, an insertion hole 125 is formed throughwhich the shoulder belt portion 11 (webbing) is inserted. The insertionhole 125 is formed into a size which allows the upper airbag 119 to movewith respect to the shoulder belt portion 11 with the shoulder beltportion 11 being inserted therethrough. Thus, in this embodiment, anupper end of the deployed upper airbag 119 is movably supported by theshoulder belt portion 11. Next, functions and effects produced by thethird embodiment of the present invention will be described.

In this embodiment, the upper end of the deployed upper airbag 119 ismovably supported by the shoulder belt portion 11. Consequently, asshown in FIG. 9, when the upper airbag 119 and the lower airbag 29 aredeployed, an upper portion of the upper airbag main body portion 121,which is forced by the deployment to be more distant from the vehicleoccupant 15, is pulled rearward (toward the vehicle occupant 15) in anarrowed direction by the extended portion 123 through which the shoulderbelt portion 11 (webbing) is inserted (the closeness between the upperairbag 27 and the shoulder belt portion 11 is maintained). Thereby, theupper airbag 119 is prevented from moving forward and thereby movingapart from the chest 19 of the vehicle occupant 15.

Next, operations of each of the vehicle occupant restraint systemsaccording to the first to third embodiments of the present inventionwill be described.

FIG. 10 is side views showing the operations of vehicle occupantrestraint systems according to the first to third embodiments of thepresent invention, and FIGS. 10( a), (b) and (c) show an initial stageimmediately following detection or prediction of a vehicle collision, anintermediate stage following the initial stage, and a late stage, wherethe lower airbag bends, following the intermediate stage, respectively.

As shown in FIG. 10( a), once the vehicle collision is detected orpredicted, the upper airbag 27 is deployed forward in the vehiclefront-rear direction from the shoulder belt portion 11, and the lowerairbag 29 is deployed forward in the vehicle front-rear direction fromthe lap belt portion 13. Here, the lower airbag 29 is deployed upwardfrom the lap belt portion 13 also, whereby an upper face of the lowerairbag 29 makes a direct contact with a lower face of the upper airbag27. Since the discharging holes 45 are formed in a front face of thelower airbag 29, a pressurized fluid (for example, a pressurized gas)inside the lower airbag 29 is discharged forward in the vehiclefront-rear direction from these discharging holes 45.

Thereafter, as shown in FIGS. 10( b) and 10(c), due to the inertialforce acting on the vehicle occupant 15, the upper body of the vehicleoccupant 15 turns forward about the neighborhood of the waist 21, andthe head 23 moves forward and downward. However, a load thereof isreceived by the deployed upper airbag 27, and the deployed lower airbag29 which supports the upper airbag 27, and forward movement thereof isrestrained. At this time, the lower airbag 29 is pressed downward by theupper airbag 27 while being pressed upward by the femoral regions 25.However, since the deployment regulating member 37 is arranged in thelower airbag 29, the upper section 41 thereof bends about the deploymentregulating member 37 with respect to the lower section 43 thereof in amanner falling down forward in the vehicle front-rear direction. Thefluid 63 is discharged forward so that the discharging holes 45 can beprevented from becoming narrow even when the lower airbag 29 bends.

The preferred embodiments described herein are illustrative and notrestrictive, and the invention may be practiced or embodied in otherways without departing from the spirit or essential character thereof.Appropriate combinations of the above described embodiments, andmodifications and changes belonging to the technical scope of thepresent invention, are all included in the scope of the presentinvention.

The present disclosure relates to subject matters contained in JapanesePatent Application No. 2008-123406, filed on May 9, 2008, thedisclosures of which is expressly incorporated herein by reference inits entirety.

1. A vehicle occupant restraint system comprising: a seatbelt devicecomprising a shoulder belt portion for restraining a part of a vehicleoccupant from a shoulder of the vehicle occupant to a chest of thevehicle occupant, and a lap belt portion for restraining a waist of thevehicle occupant; an upper airbag provided in the shoulder belt portionand configured to be deployed forward from the shoulder belt portionwhen a collision of the vehicle is detected or predicted; a lower airbagprovided in the lap belt portion and configured to be deployed forwardfrom the lap belt portion when the collision of the vehicle is detectedor predicted, the deployed upper and lower airbags coming into contactwith each other in a vertical direction; and a movement restrainingportion for restraining relative movement of the deployed upper andlower airbags in a front-rear direction, the movement restrainingportion extending downward from a lower side of the deployed upperairbag, and abutting a rear of the deployed lower airbag.
 2. The vehicleoccupant restraint system according to claim wherein: the shoulder beltportion extends from an anchor portion to a buckle portion, the anchorportion arranged on one of right and left sides of the seated vehicleoccupant near a level of the shoulders, the buckle portion arranged onthe other side of the vehicle occupant, and the movement restrainingportion joins a part of the lower side of the upper airbag on the sidewhere the anchor portion is arranged, to a part of the lower side of theupper airbag on the side where the buckle portion is arranged.
 3. Thevehicle occupant restraint system according to claim 1, wherein: thedeployed upper airbag has a concave portion where an outer surface ofthe upper airbag is concaved inwardly, and the movement restrainingportion extends in a width direction of the vehicle and joins both endsof the concave portion in the width direction.
 4. The vehicle occupantrestraint system according to claim 1, wherein the movement restrainingportion is a non-deploying portion of the upper airbag.
 5. The vehicleoccupant restraint system according to claim 3, wherein: the upperairbag is formed by joining together marginal portions of two sheetmaterials, the concave portion is formed of a concaved section where thejoined portions of the two sheet materials are arranged so as to curveinward, and the movement restraining portion is formed of a part of thesheet materials arranged in the concaved section.
 6. The vehicleoccupant restraint system according to claim 1, wherein an upper end ofthe deployed upper airbag is movably supported by the shoulder beltportion.
 7. A vehicle occupant restraint system comprising: a seatbeltdevice including a shoulder belt portion for restraining a part of avehicle occupant from a shoulder of the vehicle occupant to a chest ofthe vehicle occupant, and a lap belt portion for restraining a waist ofthe vehicle occupant; an upper airbag provided in the shoulder beltportion and configured to be deployed forward from the shoulder beltportion when a collision of the vehicle is detected or predicted; alower airbag provided in the lap belt portion and configured to bedeployed forward from the lap belt portion when the collision of thevehicle is detected or predicted, the deployed upper and lower airbagscoming into contact with each other in a vertical direction; and amovement restraining means for restraining relative movement of thedeployed upper and lower airbags in a front-rear direction, the movementrestraining means extending downward from a lower side of the deployedupper airbag, and abutting a rear of the deployed lower airbag.
 8. Thevehicle occupant restraint system according to claim 1, wherein themovement restraining portion that extends downward from the lower sideof the deployed upper airbag is positioned between an upper section ofthe deployed lower airbag and the vehicle occupant.
 9. The vehicleoccupant restraint system according to claim 1, wherein a tensile forceacts on the movement restraining portion of the deployed upper airbag.10. The vehicle occupant restraint system according to claim 2, whereinthe movement restraining portion comprises a linear member joining apart of the lower side of the upper airbag on the side where the anchorportion is arranged to a part of the lower side of the upper airbag onthe side where the buckle portion is arranged.
 11. The vehicle occupantrestraint system according to claim 5, wherein the part of the sheetmaterials arranged in the concaved section is formed to have asubstantially triangular shape.